Cylinders manufactured from steel have been used for quite a number of years for holding pressurized gases in order to permit storage, shipment, and selective use thereof. The steel cylinder must be able to not only contain the gas, but must also to withstand the impacts, stresses, and environmental conditions to which the cylinder is subject over its sometimes rather substantial life.
Because pressurized gas steel cylinders are frequently shipped from one point to another, then the Department of Transportation has issued certain rules and regulations concerning their manufacture and specifications thereabout. These regulations, among other issues, address the stress which the cylinder must withstand at its service pressure, and certain requirements intended to insure that the cylinder will not suddenly rupture other than in the event of certain unusual and extraordinary situations.
Although standard pressurized gas steel cylinders in compliance with the regulations of the Department of Transportation are known, such as in compliance with Specification 3AA, there is a need for a cylinder able to withstand an even higher stress at its service pressure and which will resist rupturing even when a fracture of the cylinder wall has occurred. The disclosed invention meets these needs, and others, by providing a steel having a high molybdenum content, a low sulfur content, and a calcium addition for inclusion shape control.